PRODUCTION OF LACTIC ACID FROM GLYCEROL BY APPLYING AN ALKALINE HYDROTHERMAL PROCESS USING HOMOGENEOUS CATALYSTS AND HIGH GLYCEROL CONCENTRATION

Rodrigues, A. K. O.; Maia, D. L. H.; Fernandes, F. A. N.

doi:10.1590/0104-6632.20150323s00003356

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Brazilian Journal of Chemical Engineering

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KINETICS AND CATALYSIS; REACTION ENGINEERING; AND MATERIALS SCIENCE • Braz. J. Chem. Eng. 32 (3) • Sept 2015 • https://doi.org/10.1590/0104-6632.20150323s00003356 copy

PRODUCTION OF LACTIC ACID FROM GLYCEROL BY APPLYING AN ALKALINE HYDROTHERMAL PROCESS USING HOMOGENEOUS CATALYSTS AND HIGH GLYCEROL CONCENTRATION

Authorship SCIMAGO INSTITUTIONS RANKINGS

Abstract

The production of lactic acid from glycerol by means of the alkaline hydrothermal process was evaluated using high concentrations of glycerol. The operating conditions that influence the hydrothermal process were studied. Temperature (250 - 280 ºC), catalyst to glycerol molar ratio (0.05 to 0.15), and water to glycerol volumetric ratio (0.8 to 1.5) were evaluated, as well as the use of NaOH and KOH as catalysts. A concentration of lactic acid of 122 g/L was obtained at 260 ºC, 0.04 NaOH to glycerol molar ratio, 1.0 water to glycerol volumetric ratio and 3 h of reaction using crude glycerol as raw material. The results showed higher lactic acid concentration and productivity than the fermentative process and the hydrothermal process carried out using low initial glycerol concentration.

Keywords:
Glycerol; Lactic acid; Hydrothermal processing; Homogeneous catalyst

Run	Temperature (ºC)	Water to Glycerol volumetric ratio (v/v)	NaOH to Glycerol molar ratio (mol/mol)	Yield (%)	Lactic Acid Concentration (g/L)	Lactic Acid Productivity (g/L.h)
1	247	31.0	0.44	67.6	26.0	8.7
2	250	31.0	0.44	76.4	29.4	9.8
3	240	27.0	0.44	51.1	22.5	7.5
4	250	31.0	0.73	51.3	19.7	6.6
5	252	31.0	0.73	53.4	20.5	6.8
6	245	27.0	0.73	50.2	22.1	7.4
7	241	31.0	1.02	47.1	18.1	6.0
8	244	31.0	1.02	50.2	19.3	6.4
9	240	27.0	1.02	43.4	19.1	6.4

Factor		Effect	p Value
Hydrothermal process carried out with low glycerol concentration
	Mean	50.13 ± 2.00	0.0001
	T	14.41 ± 3.81	0.0325
	T ²	- 8.55 ± 4.16	0.1317
	Cat	- 17.24 ± 3.34	0.0141
	Cat ²	18.19 ± 5.56	0.0467
	T x Cat	- 11.27 ± 4.55	0.0895
Hydrothermal process carried out with high glycerol concentration
	Mean	7.20 ± 1.71	0.0040
	T	3.17 ± 5.18	0.5586
	Cat	- 6.01 ± 2.15	0.0268
	T x Cat	0.50 ± 2.70	0.8579

Run	Temperature (ºC)	Water to Glycerol volumetric ratio (v/v)	NaOH to Glycerol molar ratio (mol/mol)	Yield (%)	Lactic Acid Concentration (g/L)	Lactic Acid Productivity (g/L.h)
10	260	1.0	0.04	19.9	122.5	40.8
11	260	1.0	0.07	6.9	42.2	14.1
12	260	1.0	0.11	2.3	13.9	4.6
13	270	1.0	0.07	1.8	11.2	3.7
14	270	1.0	0.11	10.3	63.4	21.1
15	280	1.0	0.04	17.7	109.2	36.4
16	280	1.0	0.07	17.2	105.9	35.3
17	280	1.0	0.11	2.1	13.0	4.3
18	270	0.8	0.07	6.2	42.5	14.2
19	270	1.3	0.09	6.0	32.9	11.0
20	270	1.7	0.12	5.0	22.9	7.6

Run	Temperature (ºC)	Water to Glycerol volumetric ratio (v/v)	KOH to Glycerol molar ratio (mol/mol)	Yield (%)	Lactic Acid Concentration (g/L)	Lactic Acid Productivity (g/L.h)
21	250	1.3	0.07	0.4	2.4	0.8
22	260	0.8	0.04	2.6	18.1	6.0
23	260	1.3	0.07	5.9	32.6	10.9
24	260	1.0	0.06	1.4	8.4	2.8
25	245	0.8	0.01	1.0	6.6	2.2
26	250	0.8	0.01	6.2	42.2	14.1
27	250	1.3	0.04	3.2	17.5	5.8
28	255	0.8	0.03	2.6	18.1	6.0
29	255	0.8	0.04	2.6	18.1	6.0
30	250	1.3	0.05	25.1	137.3	45.8

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